I have come here seeking knowledge because I can't remember this ever in my own reading but hoped someone might shed some light on the subject. I have seen several debates claiming that Thranduil was an oathbreaker/treaty breaker when he did not come to the dwarves' aid in the attack by Smaug. Is there anywhere in either letters, notes, or the books themselves where any sort of treaty or pact was made between the dwarves and elves prior to the events in the Hobbitt?

I have never encountered in any of Tolkien's writings even a hint that the Elven King (not yet called "Thranduil") in The Hobbit had ever had any dealings much less a treaty with the Dwarves of the Lonely Mountain. As the book explains in the "Flies and Spiders" chapter, the Elves were suspicious of Dwarves in general because of some dispute about treasure in "ancient days". But it is clearly stated that "Thorin's family had had nothing to do with the old quarrel".

Other than barbecued Elf. Dwarves had been most effective in resisting dragons in past battles because they wore war masks (in Beleriand at least) that dampened the effect of the flames. My feeling is that if the Dwarves couldn't defeat Smaug at Erebor, the Elves couldn't either.

Besides, book-wise, Smaug attacked suddenly, and the Elf-kingdom wasn't next door. I don't see how the Elves could have shown up to see the initial assault in the first place.

And having Thranduil riding a stag was one step too close to making him a Gary-Stu. I was surprised there was no violet-eyed elfess with a pink pony. Please visit my blog...The Dark Elf File...a slighty skewed journal of music and literary comment, fan-fiction and interminable essays.

I see his point about the last-minute addition of the Petty-Dwarves to the legends of the Naugrim, as being Tolkien's attempt to square the circle of legendary Dwarf-Elf hostility coexisting with millennia of Dwarf-Elf cooperation. But I don't think it really improves things - it messes them up. The Petty-Dwarves concept annoyingly overlaps with that of the "tame savages" Druedain, who were also redeveloped for the First Age legends following the writing of The Lord of the Rings, and in no very useful fashion either. I feel that way about a lot of Tolkien's output in the last decade of so of his writings about Middle-earth. He suspected as much, too, I think.

made no sense, at best it could be explained as a a coincidental visit, but why such an armed host of warriors?

The elf/dwarf conflict can largely be explained by the murder of Thingol and the taking of the Silmaril. He was one of three racial forefathers, not simply a ruler of a kingdom at a given point in history. He would be especially reverential as the father of Luthien who whose life, deeds and legacy were one of the principal matters of histories according to Tolkien. Further cause of racial conflict is likely due to the nature of the dwarves creation. Yavanna told Aule there would be strife between her creations and his and by extension as the Elves are so attuned to all aspects of Arda in accordance with the Music of creation and the dwarves are excluded from this then strife naturally arises.